INFLAMMATORY EVENTS IN THE BLOOD AND AIRWAYS OF GUINEA-PIGS IMMUNIZEDTO TOLUENE DIISOCYANATE

Toluene diisocyanate (TDI)-induced asthma is a common cause of occupat ional lung disease. We used a model to investigate the course of bronc hopulmonary inflammation following immunization with TDI. Guinea pigs were immunized by weekly intradermal injections and challenged with TD I 7 d after the third injection. The animals were killed at different times after challenge and prepared for histologic examination of centr al and peripheral airways, for immunohistochemical studies of T lympho cyte and eosinophil distribution, and for hematologic and serologic in vestigations. Specific IgG(1) against TDI were present only in immuniz ed animals. In immunized TDI-challenged animals there was a significan t increase in the number of metachromatic cells (at 24 h) and a late i ncrease of eosinophils (at 48 h) in the peripheral blood. Mast cells a nd eosinophils were also increased in the submucosa of central airways of immunized TDI-challenged animals. A similar pattern was observed i n the animals' peripheral airways. Additionally, a significant increas e of T-lymphocytes and eosinophils was found in the lamina propria at 6 h after exposure in immunized TDI-challenged animals as compared wit h control animals. In these immunized animals, TDI challenge caused a significant increase of eosinophils, T-lymphocytes, and CD4+ T cells. These findings indicate that intradermal injections of TDI induced a s pecific antibody response as well as an inflammatory process in both c entral and peripheral airways. T cells, particularly CD4+ T cells and eosinophils, are the key cells in the immunopathologic alterations ind uced by TDI in the guinea pig lung.